Conventionally, the image minus contour is processed as a whole, and in parallel a processing of the horizontal and vertical contours is performed for a two-dimensional image. On completion of each processing, identical for all the contours, the latter are inserted into the image according to a conventional linear procedure.
Generally the latter employs a mixer between the vertical and horizontal processed contours obtained, according to the orientation of this contour in the image, and the resulting contour is inserted directly at its position in the image. This procedure is for example described in the article: Xin Li, Michael T. Orchard: New edge directed interpolation; IEEE Trans, On Image Processing, Vol. 10, No. 10, pp. 1521-1527, 2001.
A post-filtering may moreover be performed to rectify the artifacts that may have appeared on completion of the transformation of the image. However, if the contour processing used can reduce certain artifacts appearing during the transformation of the image, for example, the appearance of halos at the level of the contours of the image, it may aggravate other phenomena, such as the appearance of oscillations (“ringing”) which may be particularly detrimental for certain applications.